“Mendicants, one who does not truly know or see old age and death should train so as to truly know old age and death. …”
“… practice meditation …”
“… rouse up enthusiasm …”
“… try vigorously …”
“… persevere …”
“… be keen …”
“… rouse up energy …”
“… persist …”
“… be mindful …”
“… use situational awareness …”
“… be diligent …”
The Linked Discourses on causality are complete.